package com.crm.interceptor;

import java.io.IOException;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.lang.reflect.Method;
import java.util.Date;
import java.util.Optional;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import com.auth0.jwt.JWT;
import com.auth0.jwt.JWTVerifier;
import com.auth0.jwt.algorithms.Algorithm;
import com.auth0.jwt.exceptions.JWTDecodeException;
import com.auth0.jwt.exceptions.JWTVerificationException;
import com.auth0.jwt.interfaces.DecodedJWT;
import com.crm.annotation.PassToken;
import com.crm.annotation.UserLoginToken;
import com.crm.entity.User;
import com.crm.service.UserService;
import com.fasterxml.jackson.databind.ObjectMapper;


public class AuthenticationInterceptor implements HandlerInterceptor {

	
	  @Autowired
	    UserService userService;
	    @Override
	    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object object) throws Exception {
	        String token = httpServletRequest.getHeader("token");// 从 http 请求头中取出 token
	        // 如果不是映射到方法直接通过
	        if(!(object instanceof HandlerMethod)){
	            return true;
	        }
	        HandlerMethod handlerMethod=(HandlerMethod)object;
	        Method method=handlerMethod.getMethod();
	        //检查是否有passtoken注释，有则跳过认证
	        if (method.isAnnotationPresent(PassToken.class)) {
	            PassToken passToken = method.getAnnotation(PassToken.class);
	            if (passToken.required()) {
	                return true;
	            }
	        }
	        //检查有没有需要用户权限的注解
	        if (method.isAnnotationPresent(UserLoginToken.class)) {
	            UserLoginToken userLoginToken = method.getAnnotation(UserLoginToken.class);
	            if (userLoginToken.required()) {
	                // 执行认证
	                if (token == null) {
	                    throw new RuntimeException("无token，请重新登录");
	                }
	                // 获取 token 中的 user userName
	                String userName;
	                try {
	                	//这里把String类型转为Integer类型
	                	userName = JWT.decode(token).getAudience().get(0);
	                } catch (JWTDecodeException j) {
	                    throw new RuntimeException("401");
	                }
	                 User user = userService.findByUname(userName);
	                if (user == null) {
	                    throw new RuntimeException("用户不存在，请重新登录");
	                }
	                // 验证 token
	                JWTVerifier jwtVerifier = JWT.require(Algorithm.HMAC256(user.getUserPassWord())).build();
	                try {
	                    jwtVerifier.verify(token);
	                } catch (JWTVerificationException e) {
	                    throw new RuntimeException("401");
	                }
	                return true;
	            }
	        }
	        return true;
	    }

	    @Override
	    public void postHandle(HttpServletRequest httpServletRequest, 
	                                  HttpServletResponse httpServletResponse, 
	                            Object o, ModelAndView modelAndView) throws Exception {

	    }
	    @Override
	    public void afterCompletion(HttpServletRequest httpServletRequest, 
	                                          HttpServletResponse httpServletResponse, 
	                                          Object o, Exception e) throws Exception {
	    }
	    
	    /**
		 * 解密
		 * @param token  token字符串
		 * @param classT 解密后的类型
		 * @param  <T>
		 * @return
		 */
	 // 密钥
		private static final String SECRET = "secret";
		// jackson
		private static ObjectMapper mapper = new ObjectMapper();

		public static <T> T unsign(String token, Class<T> classT) throws IOException {
			JWTVerifier verifier = JWT.require(Algorithm.HMAC256(SECRET)).build();
			DecodedJWT jwt = verifier.verify(token);
			Date exp = jwt.getExpiresAt();
			if (exp != null && exp.after(new Date())) {
				String subject = jwt.getSubject();
				System.out.println("解密后：" + mapper.readValue(subject, classT));
				return mapper.readValue(subject, classT);
			}
			return null;
		}
}
